Limiting reverse airflow

ABSTRACT

In various examples, a fan comprises a fan rotor, logic, and a component electrically coupled to the fan rotor to control operation of the fan rotor. The logic may determine that the component has failed. Responsive to determining that the component has failed, the logic to cause a backup component to apply power to the fan rotor, wherein applying the power causes blades of the fan to reduce spinning.

BACKGROUND

A fan may include several components, such as a microcontroller, a fan rotor, and one or more transistors.

BRIEF DESCRIPTION OF THE DRAWINGS

Certain examples are described in the following detailed description and in reference to the drawings, in which:

FIG. 1 is a conceptual diagram of an example device that may limit reverse airflow;

FIG. 2 is another conceptual diagram of an example device that may limit reverse airflow;

FIG. 3 is another conceptual diagram of an example device that may limit reverse airflow;

FIG. 4 is a conceptual diagram of an example system that may limit reverse airflow;

FIG. 5 is a conceptual diagram of an example system that may limit reverse airflow;

FIG. 6 is a conceptual diagram of an example system that may limit reverse airflow;

FIG. 7 is a flowchart of an example method for limiting reverse airflow;

FIG. 8 is a flowchart of an example method for limiting reverse airflow; and

FIG. 9 is a flowchart of an example method for performing write tracking.

DETAILED DESCRIPTION

A computing device, such as a server of desktop, may be mounted in an enclosure, which is sometimes referred to as a “case.” To avoid excessive heat buildup, which can cause the computing device to malfunction, a plurality of fans may be attached to the enclosure.

It is a common occurrence that one of these fans may fail. In the event that one of the fans fails and other fans in the system continue to operate, the high air pressure created by the functioning fans may cause the failed fan to spin in reverse. In this case, the reverse-spinning fan causes air to be pulled out of the enclosure, which undermines the purpose of the fans, which is to push air into the enclosure.

Computing systems may be designed to continue functioning properly even in the event of a fan failure. However, system designs may not take into account the effect of the reverse airflow caused by the failed fan. The techniques described herein may reduce or eliminate the outflow of air caused by the failed fan by stopping rotation of the failed fan.

A fan may fail for many reasons. A fan printed circuit board (PCB) comprises a number of components that are prone to failure including MOSFETs (metal oxide semiconductor field effect transistors), one or more fuses, and a microcontroller. The techniques of this disclosure describe techniques for limiting reverse airflow caused by the failure of components of a fan in an enclosure.

More particularly, the techniques of this disclosure are directed to techniques that cause the fan to reduce spinning in the event of a microcontroller or MOSFET failure. The techniques of this disclosure determine whether a particular component has failed, and responsive to determining that the component has failed, activate a backup component. The backup component may then apply power to the fan rotor to limit the spinning of the fan or to resume normal operation of the fan.

FIG. 1 is a conceptual diagram of an example device that may limit reverse airflow. Fan 100 is illustrated in FIG. 1. Fan 100 may be coupled to an enclosure of a computing device (e.g., a case chassis or the like). Fan 100 comprises logic 102, a component 104, a power source 106, a backup component 110, and a fan rotor 108.

Power source 106 may comprise any voltage or current source. Power source 106 may comprise one or more rails of a standard ATX or other computer power supply in various examples. Power source 106 is electrically coupled with component 104 and logic 102.

Logic 102 may comprise a microcontroller, fixed function logic, or the like. Logic 102 may control the operation of component 104 and/or backup component 110 in various examples. For example, logic 102 may output control signals to component 104 to control the operation of fan rotor 108. In various examples, logic 102 may receive a pulse width modulated signal, e.g. from a motherboard of a computing device. Based on the PWM signal, logic 102 may issue signals to component 104 to control the parameters of fan rotor 108.

Logic 102 may be communicatively and/or electrically coupled with component 104 and backup component 110. Logic 102 may determine that failed component 104 has failed. In various examples, logic 102 may determine that component 104 has failed based on a value of a pin of component 104. The value of the pin may indicate a failure state. In some examples, logic 102 may determine that component 104 may have failed based on sensing electrical parameters of component 104, such a voltage difference or current. In some examples, logic 102 may determine that component 104 has failed based on the lack of signal such as a “heartbeat” signal from component 104.

Component 104 may comprise a component such as a fuse, metal oxide semiconductor field effect transistor (MOSFET), and/or microcontroller. Although illustrated as a single component, component 104 may comprise a plurality of components in various examples. Backup component 110 may comprise a redundant component of a same type as component 104. In various examples, backup component 110 may be the same in number, or fewer in number than component 104.

Fan rotor 108 comprise a rotor for fan 100. Fan rotor 108, when supplied with power, causes blades (not pictured) of fan 100 to spin. Fan rotor 108 may be electrically coupled with component 104 in various examples. Component 104 may provide power (e.g. voltage and current) to fan rotor 108 to control the operation of fan 100, for example the rotation of the blades of fan 100, in various examples.

As described herein logic 102 may determine that component 104 has failed. Responsive to determining that component 104 has failed, logic 102 may activate backup component 110. Backup component 110 may apply power to fan rotor 108. Applying the power to fan rotor causes the blades of fan 100 to reduce spinning, e.g. in the case that the fan blades are spinning in a reverse direction.

FIG. 2 is another conceptual diagram of an example computing system that may limit reverse airflow. FIG. 2 illustrates a fan 200. In various examples, fan 200 may be similar to fan 100 (FIG. 1). In the example of FIG. 2, power source 106 is electrically coupled with a microcontroller 202, logic 102, and backup microcontroller 204.

In the example of FIG. 2, logic 102 is electrically and/or communicatively coupled with microcontroller 202, backup microcontroller 204. Although logic 102 is illustrated as being discrete from backup microcontroller 204, and microcontroller 202, logic 102 may be integrated within microcontroller 202 or backup microcontroller 204.

Microcontroller 202 may receive input signals, and may generate output signals. Microcontroller 202 may generate signals to control MOSFETs (not pictured). The MOSFETs may generate power (e.g. a current output and voltage output) to control fan rotor 108. Backup microcontroller 204 may be substantially similar to microcontroller 202. Backup microcontroller 204 may also be coupled with the MOSFETs, as well as with logic 102.

In various examples, logic 102 may determine that microcontroller 202 has failed. In some examples, Logic 102 may determine that microcontroller 202 has failed based on a value of a pin of microcontroller 202. The value (e.g. a voltage value) of the pin may indicate that microcontroller 202 is in a failed state. In various examples, logic 102 may determine that microcontroller 202 is in a failed state based on receiving an invalid value from microcontroller 202, or based on not receiving data (e.g. a heartbeat signal) from microcontroller 202.

Responsive to determining that microcontroller 202 has failed, logic 102 may activate backup microcontroller 204. Backup microcontroller 204, when activated, may take control of fan rotor 108 away from microcontroller 202. Backup microcontroller 204 may then apply a power to fan rotor 108 to cause the fan blades to reduce spinning or to resume normal operation of fan rotor 108. In various examples, to apply the power to fan rotor 108, backup microcontroller 204 may apply power to one or more MOSFETs that are electrically coupled to fan rotor 108.

FIG. 3 is another conceptual diagram of an example device that may limit reverse airflow. FIG. 3 illustrates a fan 300. In various examples, fan 300 may be similar to system 100 (FIG. 1). In the example of FIG. 3, power source 106 is electrically coupled with MOSFET 302, logic 102, and backup MOSFET 304.

In the example of FIG. 3, logic 102 is electrically and/or communicatively coupled with MOSFET 302, and backup MOSFET 304. MOSFET 302 and backup MOSFET 304 may be coupled in parallel with fan rotor 108. MOSFET 302 and backup MOSFET 304 may be wired in parallel with each other in some examples.

Although backup MOSFET 304 and MOSFET 302 are illustrated as a single MOSFET, they may comprise a plurality of MOSFETs. For example, MOSFET 302 may comprise a network of MOSFETs, such as a high-low MOSFET network. In various examples backup MOSFET 304 may comprise an equal number, or a lesser number of MOSFETs relative to a number of MOSFETs of MOSFET 302. MOSFET 302 and backup MOSFET 304 may alternatively, or in combination, provide power to fan rotor 108.

In various examples, logic 102 may determine that MOSFET 302 has failed. Logic 102 may determine that MOSFET 302 has failed based on a value of a pin of MOSFET 302 in some examples. In various examples, logic 102 may determine that MOSFET 302 has failed based on measured electrical characteristics of MOSFET 302, e.g. a sensed voltage difference or current value of MOSFET 302. In various examples, microcontroller 202 may sense current from MOSFET 302 using a current sense resistor that is coupled with MSOFET 302. If the measured electrical characteristic (e.g. the current sensed using the current sense resistor) is outside of a normal operating range, microcontroller 202 may determine that one or more of MOSFET 302 has failed.

Responsive to determining that MOSFET 302 has failed, microcontroller 202 may activate backup MOSFET 304 to apply power to fan rotor 108. In various examples, to apply the power to fan rotor 108, backup MOSFET 304 that is electrically coupled to fan rotor 108. In some examples, activating backup MOSFET 304 may reduce spinning of blades of fan 300 (e.g. if there are fewer MOSFETs in backup MOSFET 304 than the number of MOSFETs in MOSFET 302. In some examples, microcontroller 202 activating backup MOSFET 304 may allow fan 300 to resume normal operation.

FIG. 4 is a conceptual diagram of an example system for limiting reverse airflow. FIG. 4 comprises a system 400. System 400 comprises a plurality of fans, fan 402, and fan 404. Fan 402 may be similar to any of the fans illustrated in FIGS. 1-3. Fans 402, 404 may be coupled to an enclosure or chassis.

In the example of FIG. 4, fan 402 comprises a power source 106, fan rotor 108, logic 102 MOSFET 302, and microcontroller 202, and backup component 110. Logic 102 may determine that at least one of microcontroller 202 or MOSFET 304 has failed. Responsive to determining that the at least one of microcontroller 202 or MOSFET 304 has failed, logic 102 may activate backup component 110 to control spinning of the blades of fan 402.

FIG. 5 is another conceptual diagram of an example system for limiting reverse airflow. FIG. 5 comprises a system 500. System 500 comprises a plurality of fans, fan 402, and fan 404. Fan 402 may be similar to any of the fans illustrated in FIGS. 1-3. Fans 402, 404 may be coupled to an enclosure or chassis.

In the example of FIG. 5, fan 402 comprises a power source 106, fan rotor 108, logic 102, MOSFET 302, microcontroller 202, and backup microcontroller 204. Logic 102 may determine that microcontroller 202 has failed. Responsive to determining that microcontroller 202 has failed, logic 102 may activate backup microcontroller 204. Backup microcontroller 204, when activated, may apply power to fan rotor 108, and may cause fan rotor 108 to resume normal operation.

FIG. 6 is another conceptual diagram of an example system for limiting reverse airflow. FIG. 6 comprises a system 600. System 600 comprises a plurality of fans, fan 402, and fan 404. Fan 402 may be similar to any of the fans illustrated in FIGS. 1-3. Fans 402, 404 may be coupled to an enclosure or chassis.

In the example of FIG. 6, fan 402 comprises a power source 106, fan rotor 108, logic 102, MOSFET 302, and backup MOSFET 304. Logic 102 may determine that at least one of backup MOSFET 302 has failed. Responsive to determining that microcontroller 202 has failed, logic 102 may cause backup MOSFET 304 to apply power to fan rotor 108 to cause fan rotor 108 to resume normal operation. As described above, backup MOSFET may comprise one or more MOSFETs. In some examples there may be fewer of backup MOSFET 304 than the number of MOSFET(s) 302.

FIG. 7 is a flowchart of an example method for limiting reverse airflow. FIG. 7 illustrates method 700. Method 700 may be described below as being executed or performed by a system, for example, fan 100 (FIG. 1), fan 200 (FIG. 2), fan 300 (FIG. 3), system 400 (FIG. 4), system 500 (FIG. 5), or system 600 (FIG. 6). Other suitable systems and/or computing devices may be used as well. Method 700 may be implemented in the form of executable instructions stored on at least one machine-readable storage medium of the system and executed by at least one processor of the system. Method 700 may be performed by hardware, software, firmware, or any combination thereof.

Alternatively or in addition, method 700 may be implemented in the form of electronic circuitry (e.g., hardware). In alternate examples of the present disclosure, one or more blocks of method 700 may be executed substantially concurrently or in a different order than shown in FIG. 7. In alternate examples of the present disclosure, method 700 may include more or fewer blocks than are shown in FIG. 7. In some examples, one or more of the blocks of method 700 may, at certain times, be ongoing and/or may repeat.

In various examples, method 700 may start at block 700 at which point logic, a processor, or a microcontroller, (e.g. logic 102 of FIG. 1, microcontroller 202) may determine that a component (e.g. component 104), has failed. Responsive to determining that the component has failed, the method may proceed to block 704. At block 704, the logic or microcontroller may activate a backup component (e.g. backup component 110) for the failed component. The backup component may resume normal operation of the fan.

FIG. 8 is a flowchart of an example method for limiting reverse airflow. FIG. 8 illustrates method 800. Method 800 may be described below as being executed or performed fan 100 (FIG. 1), fan 200 (FIG. 2), fan 300 (FIG. 3), system 400 (FIG. 4), system 500 (FIG. 5), or system 600 (FIG. 6). Other suitable systems and/or computing devices may be used as well. Method 800 may be implemented in the form of executable instructions stored on at least one machine-readable storage medium of the system and executed by at least one processor of the system. Method 800 may be performed by hardware, software, firmware, or any combination thereof.

Alternatively or in addition, method 800 may be implemented in the form of electronic circuitry (e.g., hardware). In alternate examples of the present disclosure, one or more blocks of method 800 may be executed substantially concurrently or in a different order than shown in FIG. 8. In alternate examples of the present disclosure, method 800 may include more or fewer blocks than are shown in FIG. 8. In some examples, one or more of the blocks of method 800 may, at certain times, be ongoing and/or may repeat.

In various examples, method 800 may start at block 802 at which point logic, (e.g. logic 102 of FIG. 1), may determine that a microcontroller (e.g. microcontroller 202 of FIG. 2), has failed. In various examples, determining that the microcontroller has failed may be based on at least one of receiving, from the microcontroller, an indication that the microcontroller has failed. Responsive to determining that the microcontroller has failed (block 804), method 800 may proceed to block 806.

At block 806, the logic may activate a backup microcontroller (e.g. backup microcontroller 204 of FIG. 2) separate from the microcontroller. In various examples, activating the separate logic circuit make take control of the fan away from the microcontroller. At block 808, the logic circuit may apply power to a fan rotor (e.g. fan rotor 108 of FIG. 1) to resume normal operation of the fan.

FIG. 9 is a flowchart of an example method for limiting reverse airflow. FIG. 9 illustrates method 900. Method 900 may be described below as being executed or performed fan 100 (FIG. 1), fan 200 (FIG. 2), fan 300 (FIG. 3), system 400 (FIG. 4), system 500 (FIG. 5), or system 600 (FIG. 6). Other suitable systems and/or computing devices may be used as well. Method 900 may be implemented in the form of executable instructions stored on at least one machine-readable storage medium of the system and executed by at least one processor of the system. Method 900 may be performed by hardware, software, firmware, or any combination thereof.

Alternatively or in addition, method 900 may be implemented in the form of electronic circuitry (e.g., hardware). In alternate examples of the present disclosure, one or more blocks of method 900 may be executed substantially concurrently or in a different order than shown in FIG. 9. In alternate examples of the present disclosure, method 900 may include more or fewer blocks than are shown in FIG. 9. In some examples, one or more of the blocks of method 900 may, at certain times, be ongoing and/or may repeat.

In various examples, method 900 may start at block 902 at which point a microcontroller, (e.g. microcontroller 202 of FIG. 2), may determine that a MOSFET (e.g. MOSFET 304 of FIG. 3), has failed. In various examples, determining that the MOSFET has failed may be based on reading a value of a failure pin of the MOSFET or sensing an electrical parameter of the MOSFET (e.g. using a current sensing resistor). Responsive to determining that the MOSFET has failed (block 904), method 900 may proceed to block 906.

At block 906, the microcontroller may provide power for the fan rotor (e.g. fan rotor 108 of FIG. 3) with a backup MOSFET (e.g. backup MOSFET 304) to reduce spinning of the blades of the fan. 

1. A method comprising: determining that a component of a fan has failed; responsive to determining that the component has failed: activating a backup component for the failed component to resume normal operation of the fan.
 2. The method of claim 1, wherein determining that the component of the fan has failed comprises: determining that a microcontroller of the fan has failed, the method comprising: responsive to determining that the microcontroller has failed: activating a backup microcontroller that is separate from the microcontroller; and resuming, with the backup microcontroller, normal operation of the fan.
 3. The method of claim 2, wherein activating the backup microcontroller comprises taking control of a rotor of the fan away from the failed microcontroller.
 4. The method of claim 2, wherein determining that the microcontroller has failed comprises: determining that the microcontroller has failed based on receiving, from the microcontroller, an indication that the microcontroller has failed.
 5. The method of claim 1, wherein determining that the component of the fan has failed comprises: determining that a MOSFET (metal oxide semiconductor field effect transistor) has failed, wherein the MOSFET provides power to a rotor of the fan; and wherein resuming normal operation of the fan comprises providing, with a backup MOSFET, power to the fan rotor.
 6. The method of claim 5, wherein determining that the MOSFET has failed is based on sensing an electrical parameter of the MOSFET.
 7. A device comprising a fan, the fan comprising: a fan rotor; a component electrically coupled to the fan rotor to control operation of the fan rotor; a backup for the component; and logic, the logic to: responsive to determining that the component has failed: activate the backup component, the backup component to: apply power to the fan rotor, wherein applying the power causes blades of the fan to reduce spinning.
 8. The device of claim 7, wherein the component comprises a microcontroller, wherein the backup component comprises a backup microcontroller separate from the microcontroller, wherein responsive to determining that the microcontroller has failed, the logic to: activate the backup microcontroller; wherein to apply the power to the fan rotor, the backup microcontroller to: apply the power, with the backup microcontroller, to the fan rotor to cause the fan rotor to reduce spinning.
 9. The device of claim 8, wherein to activate the backup microcontroller, the logic to allow the backup microcontroller to take control of the fan rotor away from the microcontroller.
 10. The device of claim 8, wherein the failed microcontroller comprises a pin that indicates a failure state, the logic to: determine that the microcontroller has failed based on a current of the pin indicating the failure state.
 11. The device of claim 8, wherein the logic to determine that the microcontroller has failed based on at least one of: not receiving a signal or receiving an invalid signal value from the microcontroller.
 12. The device of claim 7, wherein to determine that the component of the fan has failed, the logic to: determine that a MOSFET (metal oxide semiconductor field effect transistor) has failed, wherein the MOSFET controls power provided to the fan rotor; and responsive to determining that the MOSFET has failed, provide power for the fan rotor with a backup MOSFET to reduce spinning of the fan.
 13. The device of claim 12, wherein the logic to determine that the MOSFET has failed based on sensing an electrical parameter of the MOSFET.
 14. A system comprising: an enclosure; a first fan coupled to the enclosure; and a second fan coupled to the enclosure, the second fan comprising: a fan rotor; and logic to: determine that at least one of a microcontroller or a metal oxide semiconductor field effect transistor (MOSFET) of the second fan has failed; responsive to determining that that at least one of the microcontroller or the MOSFET has failed: activate a backup component to control spinning of blades of the fan.
 15. The system of claim 14, the second fan comprising: a backup microcontroller that is separate from the microcontroller, the logic to: responsive to determining that the microcontroller has failed: activate the backup microcontroller; wherein to apply the current to the fan rotor, the backup microcontroller to: apply, with the backup microcontroller, power to the fan rotor to cause the fan rotor to resume normal operation.
 16. The system of claim 14, wherein to activate the backup component, the microcontroller to: responsive to determining that the MOSFET has failed: provide power for the fan rotor with a backup MOSFET to cause the fan rotor to resume normal operation. 